Okay, so I know colds can get that bad, but with how often manga portrays them getting that bad (rather than just being an annoyance), I'm left wondering how the hell the Japanese haven't died off due to apparently having the weakest immune systems in existence.
Seriously, the way manga portrays them, a case of chickenpox could wipe out half the population of Tokyo if not properly quarantined.
The seasonal flu could render the country unable to operate.